I took a look at their docs https://docs.syncthing.net/v1.27.5/users/foldertypes

And it seems similar

Src/send-only -> send files to other dest/receive-only

Dest/recieve-only -> doesn't send any file modifications or new files to other directories

Src+dest/normal -> send files to other dest and receives files from other srcs

With the option -D/-diff enabled file modifications can be synced, with newer files replacing older files